[Aavso-photometry] Web tool for mag error vs aperture radius

[Jim Jones]

Michael

You have some very nice "tool" on your web site.  Thanks for putting
them up.

I spent far more time than I should have fooling around with your SNR
calculator. According to the calculator, increasing the focal length
(with no other changes) results in an increase in SNR.  This seems
contrary to a number of authors, some of whom make  very strong and
definite statements that this isn't the case.

Jim Jones

Michael Newberry wrote:
> I've added a web tool for calculating (and graphing) the magnitude error and SNR as a function of aperture radius. The graph helps you see the effect of different instrumental parameters and observing scenarios and how to choose an "optimal" aperture. You can see how all the various parameters fold into this (for example, how does binning affect things?). The optimal radius is a function of all the parameters, including the star's magnitude. So the question arises about what to do for stars of different magnitude in the same field. The best strategy, in my opinion (and the one I've always used) is to choose the aperture size that works for the target stars, even if it is not optimal for the brighter standard stars. Then use multiple standards to beat down their errors, when possible.
>
> You can use this tool by going to http://www.mirametrics.com. Select "Web Tools" from the left menu and then select "aperture photometry optimizer" from the list.
>
> Michael Newberry
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